肾小管脂滴包被蛋白2在预测糖尿病肾脏病进展中的作用及机制

Application and mechanism of renal tubular perilipin 2 in predicting de⁃cline in renal function in diabetic kidney disease patients

目的:探讨肾小管上皮细胞中脂滴包被蛋白2(PLIN2)的表达变化能否预测糖尿病肾脏病(DKD)肾功能的减退,以及PLIN2促进DKD肾小管上皮细胞损伤的机制。方法:采用回顾性队列研究,选择12例非糖尿病患者(作为对照)和51例DKD患者为研究对象,收集人口学及实验室检查等资料。采用简化线性混合效应模型获得估算的肾小球滤过率(eGFR)斜率,Spearsman相关分析和广义线性模型预测PLIN2与DKD患者肾功能减退的关系。体内实验采用BKS-db/db小鼠和链脲佐菌素构建的糖尿病小鼠模型。体外实验采用葡萄糖处理原代肾小管上皮细胞,转染PLIN2 siRNA或过表达质粒。蛋白免疫印迹和免疫荧光染色检测PLIN2表达,油红染色检测脂滴蓄积,细胞实时能量代谢分析仪检测线粒体氧消耗率(OCR)。结果:DKD患者肾小管中的PLIN2表达水平较对照显著升高。随访24 (12,39)个月,DKD患者的eGFR斜率为-7.42(-19.77,-2.09) mL/(min·1.73 m^(2)·year)。基线时肾小管PLIN2阳性面积百分比的增大与随访期内eGFR斜率的变化显著相关[风险比(HR)=1.90,95%置信区间(CI):1.00~3.58],提示肾小管PLIN2预测DKD肾功能减退的价值。糖尿病小鼠模型肾小管中的脂滴和PLIN2表达均较对照组显著增多,葡萄糖处理造成肾小管上皮细胞中脂滴蓄积和PLIN2表达增多。干扰PLIN2显著缓解葡萄糖引起的脂滴蓄积;反之,过表达PLIN2加重葡萄糖引起的脂滴蓄积。葡萄糖处理造成肾小管上皮细胞线粒体OCR的下降在干扰PLIN2后得到缓解;然而,过表达PLIN2直接造成线粒体OCR降低。结论:肾小管PLIN2能预测DKD患者肾功能的减退。PLIN2抑制线粒体有氧呼吸,参与肾小管上皮细胞的脂滴蓄积和DKD的进展。

AIM:To investigate whether the expression of perilipin 2(PLIN2)in renal tubular cells could predict a decline in renal function in diabetic kidney disease(DKD)patients,and to explore the potential mechanisms in-volved in renal tubular cell injury induced by PLIN2 during the progression of DKD.METHODS:Control individuals(n=12)and DKD patients(n=51)were enrolled in this retrospective cohort study.Demographic and laboratory data were col-lected.A simplified linear mixed-effects model was applied to assess the estimated glomerular filtration rate(eGFR)slope.The relationship between PLIN2 and renal function decline in DKD patients was predicted by Spearman correlation analysis and a generalized linear model.BKS-db/db diabetic mice and streptozotocin-induced diabetic mice were used.Primary renal tubular cells were treated with glucose and transfected with small interfering RNA or plasmid.Western blot-ting and immunofluorescence staining were used to detect PLIN2 expression.Lipid droplets were stained with oil red O.The oxygen consumption rate(OCR)of mitochondria was measured using an extracellular flux analyser.RESULTS:The expression of PLIN2 was markedly higher in the tubules of DKD patients than in those of control subjects.After 24(12,39)months of follow-up,the eGFR slope of DKD patients was-7.42(-19.77,-2.09)mL/(min·1.73 m^(2)·year).An in-crease in the baseline percentage of PLIN2-positive tubules was significantly associated with the eGFR slope during the fol-low-up period[hazard ratio(HR)=1.90,95%confidence interval(CI):1.00~3.58],indicating that tubular PLIN2 could predict a decrease in renal function in DKD patients.Both the accumulation of lipid droplets and the expression of PLIN2 were markedly greater in the tubules of diabetic mice than in those of control mice.Glucose treatment induced lipid droplet accumulation and PLIN2 expression in renal tubular cells.Knockdown of PLIN2 significantly alleviated glucose-in-duced lipid droplet accumulation,whereas PLIN2 overexpression aggravated glucose-induced lipid droplet accumulation.The decrease in mitochondrial OCR in renal tubular cells induced by glucose treatment was alleviated after PLIN2 knock-down.However,overexpression of PLIN2 directly decreased the mitochondrial OCR.CONCLUSION:The PLIN2 ex-pression in tubules predicts a decline in renal function in patients with DKD.The PLIN2 suppresses mitochondrial aerobic respiration and contributes to the accumulation of lipid droplets in renal tubular cells to promote the progression of DKD.